decompose

Everyday

1. To rot or break down slowly, as dead plants and animals do, with help from bacteria, fungi and small creatures. tree →
2. (science) To break a substance into simpler parts or chemicals. tree →
3. (maths) To break a number or shape into smaller parts to make it easier to work with, such as 47 = 40 + 7. tree →

In the lessons

In science lessons, decomposers like worms, fungi and bacteria make dead things decompose into soil; compost heaps work this way. In maths, children «decompose numbers» (partition them) to add, subtract and multiply: 36 × 4 = 30 × 4 + 6 × 4. Phrases: «decompose into», «fully decomposed», «decompose a number».

Examples

• Leaves decompose and turn into soil. tree →
• Fungi help dead logs decompose. tree →
• A banana peel decomposes faster than a plastic bag. tree →
• Decompose 58 into 50 and 8 to add it more easily. tree →
• Plastic can take hundreds of years to decompose. tree →
• Heat can decompose some chemicals into gases. tree →
• We watched apples decompose in jars for our experiment. tree →

Note

Noun: «decomposition»; living things that do this are «decomposers». Trap: «biodegradable» things decompose naturally, but not all «green-looking» packaging does. In maths, decomposing a number does not change its value: 47 is still 47 whether written 40 + 7 or 30 + 17.